Cellulosic film



' casting surface.

' surface "ramics, plastics and for.

Patented Dec. 29, 1942 UNITED STATE 5 PATENT OFFICE CELLULOSIC rum Theodore Rudolph signor to E. I. du Wilmington, Del.,

Latour, Kenmore, N. 1., as- Pont de Nemours & Company,

a corporation of Delaware No Drawing. Application October 3, 1939,

Serial No. 297,665

18 Claims. (Cl. 106-178)- soluble cellulose derivatives (substituted celluloses) which have been applied in solution to .the

of such materials as wood, metals, ce-

the like, and the solvent evaporated, possess considerable adhesion there- When applied for protection, purposes the adhesion between the cellulose substituted derivative and the ous films of organic solvent soluble cellulose substitution derivatives are disclosed in U. S. A. Patent No. 1,458,592 (Olson). In general such procedures involve the laying of a film of dope (solution of the cellulose derivative) on to a rotating casting wheel mounted and arranged for the removal of the solvent from the dope during its rotation. The means for the solvent removal may include heating the surface of the wheel or surface. With the preferred members of the group the adhesion is reduced to such an extent that only avery slight tension is required to strip the film from the casting surfaces 'This invention had for an object the. manufacture of transparent, strong and flexible sheets or films which were undeformed and/or undistorted and/or unmarred and the production tions of matter suitable. for the casting thereof.

.A further object was todry cast toluene-ethanol (80:20) soluble ethyl cellulose into thin, strong,

- smooth, flexible sheets capable of being easily base material upon which it has been coated is a desirable property. This inherent adsurfaces adjacent thereto, together with devices such as fans for carrying the solvent away from the film. Ordinarily the speed of the wheel and the degree of heating are adiusted so that the desired amount of solvent and alloys are generally used for surfaces of the casting wheels.

In the continuous casting operation the adhesion between the partially dried film and the castbreak distortion and deformation are ouite ccmmon due to the high tension required for pulling the film away from the casting surface.

A group of materials has now been discovered which greatly decreases the adhesion betweensuch partially dried film and the metal casting is removed in somewhat less than one revolution of the casting wheel. Nickel, chromium, stainless steel and other metalsstripped from the casting wheel whileretaining 5% to 15% of the solvent of the casting dope. Further objects were to devise a means of decreasing the adhesion between a dry cast, organic solvent soluble, organic cellulose derivative and the casting surface, to facilitate the removal of partially dried, dry cast, organic cellulose derivatives from casting wheels and belts, and to'find a materials which could -be added to a dry casting solution to make removal of the film easy when only a small proportion of the solvent remains. A general advance in the art and other objects which will appear hereinafter are also contemplated.

It has now been cluding hydroxyalkyl and aralkyl) salts of fatty acids containing more than 6 carbon atoms may be incorporated in casting dopes with the result that the film formed therefrom can satisfactorily removed from the casting surface.

From the following description and specific examples in which are disclosed certain embodiments of the invention as well as details of what is believed to be the best mode for carrying out the invention, it will be apparent how the foregoing objects and related ends are accomplished. The parts aregiven by weight throughout the application.

Example I To a solution containing" 15% benzyl cellulose together with 15% cellulose) dibutyl phthalate as plasticizer dissolved in a solvent mixture consisting of 80% toluene and 20% ethanol. 2% (on the basis of the I benzyl cellulose present) triethanolamine stearate pared to a film cast from a similar of composidiscovered that the alkyl (inbe easily and I (on the'basis of the benzyl Example II cellulose) diamyl phthalate as plasticizer dissolved in a solvent mixture consisting of toluene-- ethanol 80:20, 2% (on the basis of the propyl cellulose present) benzyl trimethyl ammonium myristate was added. Film was cast from this solution on to a nickelsurface and dried. It possessed only a slight adhesion to the nickel surface when compared to a film. cast from a similar propyl cellulose solution towhich no benzyl trimethyl ammonium myristate had been added.

lose solution to which no benzyl-trimethyl ammonium laurate had been added.

Example III To a solution containing'15% ethyl cellulose together with (on the basis of the ethyl cellulose) tributyl phosphate as plasticizer dissolved in a solvent mixture consisting of 80% ethylene dichloride and methanol, 2% (on the basis of the ethyl cellulose present) diethanolamine oleate was added. Film was cast from this solution on to a nickel surface and dried. It possessed only a slight adhesion to the nickel surface when compared to a filmcast from a similar ethyl cellulose solution to which no diethanolamine oleate had been added.

Example IV To a solution containing 15% ethyl cellulose together with 15% (on the basis of the ethyl cellulose) triethylene glycol dihexoate as plasticizer dissolved in a solvent mixture consisting of 80% toluene and 20% ethanol, 2% (on the basis of the ethyl cellulose present) monoethanolamine oleate was added. Film was cast from this solution on to a nickel surface and dried. possessed only a slight adhesion to the nickel surface when compared to a film cast from a similar ethyl cellulose solution to which no monoethanolamine oleate had been added.

Example V To a solution containing 15% ethyl cellulose together with 15% (on the basis of the ethyl cellulose) butyl phthalyl butyl glycollate as plasticizer dissolved in a solvent mixture consisting of 80% toluene and 20% ethanol, 2% (on the basis of the ethyl cellulose present) benzyl trimethyl ammonium myristate was added. Film was cast from this solution on to a nickel surface and dried. It possessed only a slight adhesion to the nickel surface when compared to a film cast from a similar ethyl cellulose solu-, tion to which no benzyl trimethyl ammonium myristate had been added.

- Example VI To a solution containing 15% benzyl cellulose together with 15% (on the basis of the benzyl cellulose) dibutyl phthalate as plasticizer dissolved in a solvent mixture consisting of 80% toluene and 20% ethanol, 2% (on the basis of the benzyl cellulose present) benzyl trimethyl ammonium palmitate was added. Film was cast To a solution containing 15% propyl cellulose together with 15% (on the basis of the propyl Example.- vm

To a solution containing 15% ethyl benzyl cellulose together with 15% (on the basis of the ethyl benzyl cellulose) dibutyl phthalate as plasticizer dissolved in a. solvent consisting of dioxane, 2% (on the basis of the ethyl benzyl cellulose present) benzyl trimethyl ammonium laurate was added. Film was cast from this solution on to a nickel surface and dried. It possessed only a slight adhesion to the nickel surface when compared to a film vcast from a similar ethyl benzyl cellulose solution. to whichno benzyl trimethyl ammonium laurate had been added.

The dope or cellulose derivative solution containing the strip agentsof the invention may be handled and cast in the same manner. as the dopes previously known to the art. I

The most marked decrease in adhesion be-v tween the film and the casting wheel surface had been noted when the casting surface was nickel.

In the preferred mode of operation the film is stripped from the casting wheel while it still contains 5% to 15% of the solvent.

This invention is not limited to the ethyl cellulose of the specific examples although it peculiarly appe gins thereto. In general it is, with considerable efficacy, applicable to all kinds. of organic derivatives of cellulose which are soluble in organic liquids (solvents), including cellulose esters such as cellulose acetate, cellulose propionate, cellulose butyrate, and the'like; mixed esters, such as cellulose aceto-propionate, cellulose aceto-butyrate and the like; cellulose ethers, such as methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, benzyl cellulose and the like; mixed ethers, such as ethyl benzyl cellulose and the like; and mixed cellulose ether esters such as ethyl cellulose acetate, and the like.

The alkyl amine salts of fatty acids comprehended by the present invention are those of fatty acids containing at least '7 carbon atoms.

Preferably the fatty'acids contain 12to 20 carbon atoms or more. Especially suitable for the purposes of the present invention are the benzyl trimethyl ammonium salts of lauric. myristic, palmitic, oleic and stearic acids. The results obtained with the triethanolamine, diethanolamine and monoethanolamine salts of the aforementioned acids are also outstanding.

In the preferred embodiments of the invention the alkyl amine salt of the fatty acid is present in amount within the range of 0.5% to 5% by weight on the basis of the cellulose derivative. Higher concentrations are not excluded and may be used in order to secure specific results.

The alkyl amine salts of fatty acids may be used singly or in any combination, and it is to be understood that the invention is. not limited to the specific alkyl amine salts listed above or in the specific examples.

The stripping agentsof this invention may be ticizer and 2% incorporated in the casting dope in any desired manner. If preferred they may be predissolved and the solvent used for dissolving the cellulose derivative. Ordinarily they are incorporated into the solvent simultaneously with the cellulose derivative. In some instances 'it h as been found convenient to add the stripping agent to the solution of the cellulose derivative.

- of toluene-ethanol containing 15% Many of the advantages of the present invention will be apparent from the preceding portion of the specification. Specific mention may be made of the fact that by this invention it is possible to easily and satisfactorily remove the partially dried, dry cast film from a metal or alloy casting wheel at elevated temperatures, and that all danger of tearing or deforming the dry cast film at the stripping point (or line) due to the pull required to separate the film from the casting surface has been removed. The advantage of incorporating in a casting solution a material which decreases the adhesion between the film cast therefrom and the casting surface without undesirably affecting the transparency and surface characteristics of the those skilled in the art.

I claim:

1. A plasticized, organic solvent soluble, cellulose substitution derivative film containing 0.5% to 5% of benzyl trimethyl ammonium laurate.

2. A film of ethyl cellulose containing 0.5% to 5% of benzyl trimethyl ammonium salt of fatty acid containing at least '7 carbon atoms;

3. The product of claim 2 when the fatty acid contains 12 to 20 carbon atoms.

4. A film of ethyl cellulose containing 0.5% to 5% of benzyl trimethyl ammonium salt of acid material from the group consisting of lauric acid. myristic acid, palmitic acid, maleic acid and stearic acid.

5. A film of ethyl cellulose containing 0.5% to 5% of benzyl trimethyl ammonium laurate.

6. A casting dope comprising essentially a 15% solution of ethyl cellulose in organic solvent containing 15% (based on the ethyl cellulose) plas- (based on the ethyl cellulose) benzyl trimethyl ammonium laurate.

7. A casting dope comprising essentially a 15% solution of ethyl cellulose in an 80:20 mixture of toluene-ethanol containing 15% (based on the ethyl cellulose) diamyl phthalate and 2% (based film will be obvious to 80:20 mixture (based on the ethyl cellulose) butyl phthalyl butyl glycolate and 2% (based on the ethyl cellulose) benzyl trimethyl ammonium myristate.

10. A casting dope comprising 15% solution of ethyl cellulose in organic solvent containing15% (based on the ethyl cellulose) .plasticizer and 2% (based on the ethyl cellulose) benzyl trimethyl ammonium palmitate.

solution of ethyl cellulose in an 11. A casting dope compr sing essentially a' 15% solution of ethyl cellulose in an 80:20 mixture of toluene-ethanol containing 15% (based on the ethyl cellulose) dibutyl phthalate and 2% (based on the ethyl cellulose) benzyl trimethyl ammonium palmitate. v

12. A casting dope comprising essentially a 15% solution of ethyl cellulose in organic solvent containing 15% (based .on the ethyl cellulose) plasticizer and 2% (based on the ethyl cellulose) benzyl trimethyl ammonium salt of fatty acid containing at least 7 carbon atoms.

13. A plasticized organic solvent soluble cellulose substitution derivativeffilm containing 0.5% to 5% of benzyl trimethyl ammonium salt of fatty acid containing at least '7 carbon atoms and 5% to 15% organic solvent for the cellulose V substitution derivative.

substitution derivative taining 15% on the ethyl cellulose) benzyl trimethyl ammonium laurate.

8. A casting dope comprising essentially a 15% solution of ethyl cellulose in organic solvent containing 15% (based on the ethyl cellulose) plasticizer and 2% (based on the ethyl cellulose) benzyl trimethyl ammonium myristate.

9. A casting dope comprising essentially a 15% v 14. A plasticized organic solvent soluble cellulose substitution derivative film containing 0.5% to 5% of benzyl trimethyl ammonium laurate and 5% to 15% residual casting solvent consisting of an :20 toluene-ethanol mixture.

15. A plasticized organic solvent soluble cellulose substitution derivative film containing 0.5% to 5% of benzyl trimethyl ammonium salt of fatty acid from the group consisting of lauric acid, myrlstic acid, palmitic acid and stearic acid and 5% to 15% organic solvent for the cellulose substitution derivative.

16. A plasticized organic solvent soluble cellu lose substitution derivative film containing 0.5% to 5% of benzyl trimethyl ammonium salt of fatty acid containing at least '7 carbon atoms.

17. A casting dope comprising essentially a 15% solution of organic solvent soluble cellulose in organic solvent con- (based on the cellulose derivative) plasticizer and 2% (based on the cellulose derivative) benzyl trimethyl ammonium salt of fatty acid containing at least '1 carbon atoms.

18. A plasticized organic solvent soluble ethyl cellulose film containing 0.5% trimethyl ammonium laurate and 5% to-15% residual casting solvent consisting of an 80:20

toluene-ethanol mixture.

THEODORE R. LATOUR.

essentially a to 5% of benzyl- 

